Preparation and Properties of PTFE-containing Gas Diffusion Layer for Fuel Cell
氣體擴散層 ； 聚四氟乙烯 ； 燃料電池 ； poly (tetrafluoroenthylene) ； Fuel Cell ； Gas Diffusion Layer
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本研究以碳黑及石墨為導電材料、聚四氟乙烯(PTFE)粉末及PTFE分散液為黏結劑，製備三種含PTFE系列之氣體擴散層。探討添加不同粒徑之PTFE分散液及改變組成對氣體擴散層電性質及物理性質之影響。 結果顯示，本研究成功地製備出具機械強度之片狀氣體擴散層；掃描式電子顯微鏡之影像證實，PTFE顆粒在氣體擴散層中分散良好。導電度方面，當PTFE分散液含量及粒徑增加時，氣體擴散層之導電度有降低之趨勢；但整體而言碳系列導電度最高，可達0.342 S/cm優於石墨/碳系列，而石墨/碳系列優於石墨系列。機械性質方面，當PTFE分散液含量增加時，氣體擴散層的Yield Stress明顯增加；其中石墨系列提昇最為顯著，可達1.7MPa。 此外，由於PTFE粉末添加量增加，此三系列氣體擴散層之接觸角提升10°~30°。再者，氣體滲透測試結果顯示，碳系列之氧氣滲透率最佳，達到10-2 (cm3 (STP)‧cm / sec‧cm2‧cm-Hg)，優於商用碳紙。 綜合本研究結果，所製備之含PTFE氣體擴散層均為具有機械強度、導電度、疏水性與氣體滲透性之氣體擴散層，其中以碳系列之綜合性質較佳，有應用於燃料電池之潛力。
In this thesis, the conductive materials, carbon black, graphite and their mixtures, and the binding materials, poly(tetrafluoroethylene) (PTFE) powder and PTFE dispersion, were mixed to prepare three series of PTFE-containing gas diffusion layer (GDL).The effects of the PTFE particle size and the composition on the electronic conductivity and the related physical properties of the GDLs were studied. The results showed that the PTFE-containing GDL sheets with various compositions were successfully prepared by a combination of mixing and calendering process. The SEM micrographs showed that the PTFE powder was well-dispersed in the GDL matrix. It was found that the conductivities of the carbon system are higher than that of the graphite/carbon system and that of the graphite/carbon system are higher than that of the graphite system. However, as the PTFE dispersion content and its particle size increased, the conductivities were slightly decreased for all types of the GDLs. As increasing the PTFE dispersion content, the yield stress was significantly increased in all the as-prepared GDLs, especially in the graphite system. In addition, the contact angles of the GDLs, including the advancing angle and the receding angle, increased about 10°~ 30°due to the presence of PTFE powder. Furthermore, the results of gas permeability measurement showed that the average oxygen permeability of the carbon system was about 10-2 (cm3 (STP)‧cm / sec‧cm2‧cm-Hg), which is better than that of the commercial carbon paper, and is the highest among the three types. According to the results, these as-prepared PTFE-containing GDLs showed good mechanical strength, conductivity, hydrophobicity and gas permeability, especially in the carbon system. They can be potential GDL materials of fuel cell.
理學院 > 化學研究所